01 - Line a baking sheet with parchment paper or a silicone baking mat to prepare for the cooled pralines.
02 - In a heavy-bottomed saucepan, combine granulated sugar, light brown sugar, whole milk, unsalted butter, and fine sea salt over medium heat. Stir continuously until the butter melts and the mixture reaches a rolling boil.
03 - Attach a candy thermometer to the side of the pan. Continue to boil, stirring frequently, until the mixture registers 238°F (soft-ball stage), typically taking 8 to 10 minutes.
04 - Remove the saucepan from heat. Immediately stir in the pure vanilla extract and pecan halves. Continue stirring vigorously for 2 to 3 minutes until the mixture thickens and achieves a creamy, yet still pourable, consistency.
05 - Working swiftly, spoon individual portions of the praline mixture onto the prepared baking sheet, ensuring adequate spacing between each. Allow them to cool completely at room temperature until firm, approximately 20 to 30 minutes.
06 - Transfer the set pralines to an airtight container and store at room temperature for up to one week to maintain freshness.